What are some alternatives?
SendBird - SendBird is messaging-as-a-service.
1Password - 1Password can create strong, unique passwords for you, remember them, and restore them, all directly in your web browser.
Twilio - Brings voice and messaging to your web and mobile applications.
Lastpass - LastPass is an online password manager and form filler that makes web browsing easier and more secure.
Plivo - Plivo's Voice API enables businesses to build Voice apps to reach customers globally in 200+ countries. Try Plivo's Voice API for free. Instant Sign Up.
KeePass - KeePass is an open source password manager. Passwords can be stored in highly-encrypted databases, which can be unlocked with one master password or key file.